In the case of motor vehicles, due to the increasing number of technical components, an optimization in terms of the design volume is required in order to ensure the desired array of functions by the placement of the components. For this reason, large-volume air conditioning components such as are familiar from stationary climate control systems in the form of mixing chambers, flow baffles and swirling devices, also cannot be used in motor vehicles on account of the tight space conditions.
An additional requirement for a climate control system of a motor vehicle which conditions a supplied air mass flow, possibly breaking it up and directing the individual air mass flows into different regions of the vehicle, is to provide air mass flows of different temperature to different air outlets of the climate control system depending on their location and function. The supplied air mass flow is taken through different heat exchangers, so that the air is cooled down and dehumidified, and if necessary reheated, before being taken to the passenger space. For example, the air is blown into the foot space as well as through openings in the dashboard into the passenger space and furthermore it is taken directly to the windshield via outlets, in order to keep it free of condensation or to defrost it.
In air conditioning systems of this kind with regulation at the air side, the air mass flow being supplied to the passenger space is divided by means of a flap, also known as the temperature flap, into two partial air mass flows. The required temperatures of the air flow volumes are adjusted by means of the temperature flaps and various regulating mechanisms. One partial air mass flow is taken through a heating heat exchanger situated in the lower region of the system and heated. At the same time, the second partial air mass flow flows as cold air bypassing the heating heat exchanger. The two partial air mass flows of different temperature are then mixed to achieve the desired target temperature.
In traditional air conditioning systems the partial air mass flows are not completely mixed. Different temperatures occur at the different air outlets into the passenger space in intermediate positions of the temperature flap. The differing temperatures of the air mass flows at the different outlets, such as foot space, dashboard, and windshield ventilation, are known as temperature stratification.
To decrease the stratification between given outlets, warm air ducts are provided, for example, especially to direct warm air toward the windshield outlet, which on the one hand detract from the air flow and the acoustics, being an additional element, and on the other hand cause higher costs.
Other known air conditioning systems have a temperature flap in connection with an enlarged mixing zone, which is configured so as to take the cold air mass flow in the direction of the warm air mass flow and take the air mass flows through the enlarged mixing zone for an adequate mixing. The quality of the mixing is achieved here through the size of the mixing zone.
Alternatively or additionally, the air conditioning systems especially in the area of the mixing zone are configured with deflectors or baffles as narrowing elements or throttling elements in order to generate turbulence within the air mass flows being mixed. With the additional plates narrowing the flow cross section for the air mass flow, the flow velocity is increased. As a drawback, the pressure loss equally increases.
It is likewise known from the prior art how to design the air conditioning system so that the warm air mass flow and the cold air mass flow are taken to strike against each other frontally and then mix, for a better blending.
Other designs of traditional systems have baffles, which block the different air mass flows at certain positions as needed within the system, obstruct the passageway and thus prevent the air from flowing through.
The deflectors, baffles, narrowing elements or throttling elements are fashioned for example at the temperature flap itself.
There are also known in the prior art systems with more than two flow paths for the air, in which the air has different temperatures within the flow paths.
From EP 1 336 517 A1 there is known a climate control system with an evaporator arranged in an air duct and a heating heat exchanger arranged thereafter in the flow direction of the air. The air mass flow conditioned in the evaporator can then be divided into three different flow paths, one flow path being the warm air duct and taking the air through the heating heat exchanger and the other two flow paths being cold air ducts or bypasses and taking the air past the heating heat exchanger. The different flow paths serve to avoid a strong stratification and thus improve the temperature distribution in the air mass flow.
However, the climate control system with the sliding flaps and/or rotating flaps as well as the associated driving technology has a very complicated control system for the air mass flows through or past the heating heat exchanger. Furthermore, the climate control system is designed with a plurality of mixing chambers and requires a large installation space.
There are alternatives known from the prior art to the design of climate control systems with a plurality of sliding flaps and/or rotating flaps and the associated driving technology.
Thus, from DE 196 03 126 A1 there is known a motor vehicle climate control system for the selective opening of at least three outlets. The climate control system comprises, besides a housing, a rotating shaft which is mounted to rotate in the housing and an arched rotating slide which is connected to the rotating shaft. The rotating slide has a plurality of openings and a driving means for turning the shaft. The housing is designed with a plurality of ducts leading to the outlets, whose entrance openings are arranged along the peripheral surface of the rotating slide. By means of the rotating slide, the entrance openings of the ducts are opened and/or closed, so that the air flow arriving with uniform temperature from a mixing chamber is divided up among several ducts.
It is characteristic of the systems known in the prior art that they either have additional elements which are very costly in terms of hardware, and which furthermore require additional space, costs, as well as additional installation expense, and which entail a corresponding maintenance expense. Moreover, the additional installations produce restriction and narrowing of the flow ducts and thus cause increased pressure losses in the air flow, which in turn leads to an increased power demand and thus energy consumption, as well as lower efficiency of the air conditioning system and thus of the entire motor vehicle.
Moreover, the flap geometries known in the prior art besides the definite flow losses also produce loud flow noises. Vibrations can be produced by the swinging of the flaps.